Radius-grinding apparatus



Nbv.l4, 1958 o; SCHEUBECK- 5 RADIUS-GRINDING APPARATUS Filed Aug. 30.1955 v s Sheets-Sheet 1 //v VENTUR OSKAR SCHEUBECK ATTORNEYS Nov.- 4,1958 v o. S-CHEUBECK 2 ,858,649

RADIUS-GRINDING APPARATUS Filed Aug. 30'. 1955 A s Sheets-Sheet 2 FIG. 2

/N VE N TOR OSKAR SCHEUBECK BY Mf/ZAL A TTORNE Y5 O. SCHEUBECKRADIUS-GRINDING APPARATUS Nqv. 4, 1958 3 Sheets-Sheet 3 Filed Aug. 30.1955 FIG. 4

OSKAR SCHEUBE'CK BY M ATTORNEYS United States Patent RADIUS-GRINDINGAPPARATUS Oskar Scheubeck, Regeusburg, Germany Application August 30,1955, Serial No. 531,539

Claims. (Cl. 51-33) This invention relates to a radial grindingapparatus.

In engineering, especially in the case of milling cutters, the taskoften occurs of grinding rounded corners with precise radius.

The arrangements provided hitherto for this purpose consisted of agrinding .apparatus with a cup-shaped grinding wheel and a pivotingarrangement receiving the workpiece to be ground, inthe case underconsideration a milling cutter. The cutter could here be oriented byslide guides within the pivoting device in the desired manner and wasbrought up, for the purpose of grinding, to the side or edge of thegrinding wheel and pivoted back and forth through a certain angle, forexample about 90, when a rounded ground part was produced on the cutter.

However the known arrangements possess substantial disadvantages. As aresult of the difiiculty of orientation of the workpiece the workingrequires a considerable time, normally a number of hours. Then theaccuracy of the ground face remains limited, and does not correspond tothe reguirements made of modern milling tools. There is also theunwieldiness of the operation due to the considerable pivoting masses ofthe cutter-securing and adjusting arrangement. Furthermore thecup-shaped grind-' ing wheel signifies a'considerable expenditure ofabrasive material, where it must also be considered that the workingedge of the grinding wheel easily suffers damage and thereforethe'grinding operation becomes irregular. Furthermore even when thegrinding wheel is undamaged the danger of undesired formation of grooveson the workpiece is very great. Finally due to the circular working edgethe ground face of the workpiece does not become cylindrical, asdesired, but more or less wasted. In order to reduce this phenomenon, itis necessary to work with the greatest possible radius of the grindingwheel. However this again has other disadvantages, such as wobbling ofthe wheel etc., as its results.

It is the task of the invention to avoid all these disadvantages and toprovide an arrangement which permits a maximum of accuracy of the groundface and a significant saving of time, with very simple and convenientoperation and avoidance of large pivoting masses and large grindingwheels.

In accordance with the invention in the case of the new radial grindingapparatus the workpiece to be ground, for example a milling cutter, isnot pivoted as in the known case, but is mounted stationarily during thegrinding operation, While a rotating grinding element, for example aBosch or compressed air grinder, is arranged on a circularly movedswivelling member. Since a cylinder of very small diameter is suflicientas grinding element, for the drive of which a light motor is suflicient,a swivelling element is obtained the mass of which amounts to only 'afraction of the pivoting mass of the former radial grinding apparatuses.The operation of the swivelling element is therefore as easy as can be,so that the operator is subjected to substantially less fatigue. At thesame time the orientation of the workpiece, in relation to the knownarrangement, is significantly facilitated.-

Furthermore the ground face is also exactly cylindrical, in the case ofcylindrical grinding elements, or corresponds to the generating curve ofthe grinding cylinder in.each case, while in the known case only theaforementioned waist-shape can be obtained.

Usually in the case of milling cutters a clearance angle or abacking-off clearance is desired. This can be achieved in the case ofthe invention, by making the axis of the grinding arrangement pivotablethrough a certain angle.

An angle scale is preferably provided for the setting of the grindingaxis, on which scale the measure of the clearance angle can be read ofidirectly. For practical operation it is further proposed to make thegrinding device ad-' justable or displaceable in the radial direction onthe swivelling element, in order to move the grinding tool nearer to orfurther from the workpiece in the desired manner. The displacement canbe effected through a set screw, which can be provided with a scale.

The arrangement is expediently here made such that a special handle isprovided with the aid of which the grinding device can be lifted by asmall amount from the workpiece during the changing of the workingposition or during the transition from one cutter tooth to the next,independently of the working setting, in order to render possible theunhindered passage of the tooth. The lifting off here takes placeagainst a spring force which automatically returns the grinding deviceinto the original position on release of the handle.

The invention further provides measures in order to set the desiredradius on a scale before the arrangement is set in operation. This takesplace with the aid' of a hollow prism, preferably of right-angled shape,which serves as a kind of template, and is insertable in a boreconcentric with the swivelling axis, the edge of the hollow prismcoinciding with the swivelling axis in the zero position. Bydisplacement of the edge of the prism out of the swivelling 'axis orzero position the radius of the future ground surface is determined andcan be set or read off on an appropriate scale. Due to the fact thatthereupon the workpiece is pushed into the template to the stop, theorientation of the template is transmitted to the workpiece and thus thegrinding radius is also determined for the latter.

-In a further development of the invention a resiliently movable supporttongue is provided for the grinding of milling cutters, which bearsduring the grinding against the front of the tooth which is just to beground, while on tooth-changing or during the passing of the tooth itautomatically deflects resiliently and thereafter returns again to thesupporting position. The operator therefore merely has to rotate themilling cutter through a small angle and need not trouble about thesupporting means.

-In order to render possible a rapid and exact orientation of theworkpiece in relation to the template and'the grinding element anintermediate arm is provided on the base plate of the apparatus, whicharm is pivotably and securably mounted on the base plate, and upon whichin turn the workpiece bracket is pivotable and securable. Furthermorestops are arranged on the base plate, which permit of securing the pivotangle of the swivelling element andwhich are either displaceable in acircular guide path or insertable in appropriate setting holes.

An example of embodiment of the invention is represented in the figures,wherein: V

Figure 1 shows the plan view of the radial grinding apparatus inaccordance with the invention,

Figure 2 shows a lateral elevation,

Figure 3 shows the prism, seen from the side,

Figure 4 shows the prism with the workpiece, seen from above.

, In the figures, 1 is a base plate, uponwhich an intermediate arm 3 ispivotably mounted at 2. This arm is securable in a desired swivelledposition with a clamping device 4, which engages in a guide groove 5 ofthe base plate. At the same time a support bracket 6 for the workpiece 7ispivotably mounted on the spindle of the clamping device, and can besecured similarly in its swivelled position by a clamping device 8. Theworkpiece, for example a milling wheel 7, is clamped fast upon a bearingjournal 9 by a nut 10 and will be varied in its rotational position withthe aid of a knurled handle 11. A support tongue 12 (Figure 2) servesfor securing the rotational position in each case, being mounted at 13for pivoting through a small angle and being drawn by a spring (notshown) automatically into the supporting position or in the directiontowards the workpiece 7.

For the working of the workpiece there serves a grinding cylinder 14,which is axially adjustablev by means (not further shown) in a retainingarm 15 and is driven by an ordinary grinding motor 16. The retaining arm15 is a part of a stand which consists of the upper part 17 and thelower part 18, which are adjustable in a circular guide 19 in relationto one another. The centre point of the circular guide 19 coincides withthe working point 20, so that on a shifting of the stand parts17, 18 theaxial direction of the grinding device 14 is pivoted, without theworking point 20 being substantially displaced. The angle of pivotingcan be ascertained on a scale (not shown) of the guide path 19. Asmentioned at the outset, it determines the measure of the clearanceangle of the ground surface.

A foot 21 formed on the bottom part 18 of the stand is displaceable in aguide prism 22 of a swivelling; element 23. The swivelling element- 23is pivot-ably mounted about a journal 24, the axis 25 of whichleadsthrough the centre-point of the radius of curvature of the groundsurface. The journal 24 possesses a con' centric bore 26,into whicheither the support pin 27 of the support tongue 12 or a pin 28 of atemplate 29 can be inserted, the details of which may be seenfrom-Figures 3 and 4. The essential measurement part' of the templateconsists of a hollow prism. 30, the edge 31 ofwhich coincides with theaxis 25, if the prismisin" the zero position; It can be moved out ofthis position with the aid of a set screw 32, when a mark 33 indicatesona scale 34 the measure of the eccentricity and thus the radius of thesurface to be ground, in millimetres.

For the removal of the grinding element 14 from the workpiece 7 duringthe change of working there is provided a lifting-off device, consistingof a handle 35 which is supported at 36 on a support bracket 37 oftheswivelling element 23 in pivotable fashion. If the handle- 35' ispivoted out of the position as illustratedin the direction, the stand17, 18 is lifted ofi with the grinding cylinder 14, against the force ofa spring 38, from the workpiece 7, and after shifting of the-workpieceand release of the lever 35 automatically returns into its restposition. With the aid of a set screw 39 in combination with a scale 40the stand 17, 18 and thus the grinding cylinder 14 can be displaced inthe guide prism 22 and moved towards or away from the workpiece 7.

Stops 41, 42, which are adjustable in a circular guide path 43 of thebase plate, serveto limit the pivoting angleof the swivelling element 23to the desiredamount, preferably 90.

The apparatus is used in the following manner:

1 Setting A radius with r=5 mm. is to be trued for'example on a millingwheel-i with rounded corners. For this'purpose firstly the template 29is inserted with the pin-28 in the bore 26, and with the aid of the setscrew'32 the setting mark 33 'is set to the numeral 5:5- mm. Then afterrelease of the clamping devices 4'and8 the workpiece 7 is shifted untilthe edges of the milling tooth to be-worked bear againstthetace's w ofthe hollow prism.

The workpiece is clamped fast in this position, the prism is pushed alittle further outwards by means of the screw 32 if necessary, the pin28 is removed from the bore 26 and the prism is replaced by the supporttongue 12, which is now inserted with its pin 25 in the bore 26.

The stand 17, 18 is here removed far enough from the workpiece with theaid of the threaded spindle or set screw 39, in order to avoid damage tothe milling cutter 7 and also'to the grinding cylinder 14. The stops 41,42 are so shifted in the guide path 43 that the pivoting angle of theswivelling element 23 amounts to about 2. Grinding The upper stand part1 7 with the clamped-in electric or compressed air grinding motor 16 andthe grinding cylinder 14 is rotated through the desired angle, forexample 5, out of the vertical, utilising the guide 19, and secured inthis position. Thereupon the lower stand part 18 is displaced in theguide prism 22 of the swivelling element 23 with the aid of the setscrew 39 in the direction a, that is to say towards the workpiece; 7,until the rotating grinding cylinder 14 comes into contact with themilling. tootlrto be ground. Now the swivelling; element is moved aboutthe pin 24 from the stop 41 to the stop 42 inthe direction i'k, wherebythe grinding cylinder 14 sweeps over an arc of 90 about the axis 25, andthus grinds the desired radius s.

3. Tooth shifting The swivelling element 23 is brought into the initialpositionand the grinding cylinder 14 is removed from the workpiece 7 bythe handle 35. Now the milling cutter 7 is rotated one tooth further,with the knurled disc 11-, when the stop tongue 12 mounted resiliently.for rotation about the'point 13 is lifted. ofi in the direction 1 by thecutter tooth sliding past. The resiliently held stop tongue 12 jumps inthe direction e into the gap following' the tooth moved away, andsupports the next tooth which is now to be ground. The milling cutter 7can be clamped fast in this position, but usually it is suflicient ifthe milling cutter tooth is pressed manually with the aid of the knurleddisc 11 upon the stop tongue 12, in order to secure the precise positionof the tooth. This last-described manner of holding the milling cuttershortens the overall working time. If the handle 35 is slowly released,the compression spring 38 returns the stand 17, 18 and the grinding tool14 in the direction a into the initial position, so that now the nexttooth is worked in exactly the'same manner as the preceding one.

It is a special advantage of the new arrangement that wear upon'thegrinding tool has no influence upon the grinding radius, since this isdetermined solely by the orientation of the workpiece in relation to thetemplate 30 displaced out of the central position; As may be seen, incomparison with the'forrner cup-like, large grinding plates, a simplegrinding cylinder of small diameter, the abrasive material of which canbe completely used up, is sufiicient. The. operation of the entirearrangement is so easy and rapid that the working time can be reduced toa small fraction of the former working time, without particular strainupon the operator, who can carry out the work sitting comfortably.

I claim:

1. In a radius grinding apparatus of the type described,

' in combination, means for holding a work piece stationary during thegrinding operation, rotatable grinding means arranged on a swivellingelement and suitable for being pivoted about a pivot axis around thecenter of curvature of a surface of the work piece which is to beground, said grinding means including a grinding cylinder' and a drivingmotor connected thereto for driving the same, said cylinder and motorbeing arrange'd'coaxially with respect to each other, support means forsupporting said grinding means on said swivelling elementin such amanner that said pivot axis extends substantially parallel tothe axis ofrotation of said grinding means, and adjustable mounting means foradjustably mounting said grinding means on said swivelling element insuch a manner that the angle between the common axis of said cylinderand motor and said pivot axis may be varied to correspond to theclearance angle of the ground surface.

2. The combination as described in claim 1, wherein said support meansis adjustable in a direction transverse to said pivot axis, thecombination further comprising means for removing said support meanswith said motor and said cylinder, spring means urging said supportmeans into adjusted position, and a pivotable handle connected to saidsupport means whereby said support means can be temporarily displacedagainst the action of said spring means to permit movement of said workpiece without changing the adjustment of said grinding means.

3. The combination as described in claim 1, wherein said swivellingelement is formed with a bore arranged concentrically with respect tosaid pivot axis, the combination further including an adjusting devicecomprising a pin, a template and a hollow prism, said adjusting devicebeing positioned within said bore through the intermediary of said pin,a support comprising a pin and a support tongue, said last-mentioned pinbeing suitable for being positioned in said bore, said adjusting devicethus being replaceable by said support.

4. The combination as described in claim 1 wherein said adjustablemounting means for said motor and said 6 cylinder comprise two partshaving at their junction a slot forming the segment of a circle thecenter of which coincides with the spot of grinding, said mounting meansthus allowing for changing the clearance between work piece and grindingmeans without changing the location of the spot of grinding.

5. The improvement as described in claim 1 wherein said means forholding the work piece stationary during the grinding operation comprisea swivelling arm and a base plate, said swivelling arm being mounted onsaid base plate, and means for arresting said work piece on saidswivelling arm, thus allowing said arrested work piece to be movedtogether with said swivelling arm into a predetermined position.

References Cited in the file of this patent UNITED STATES PATENTS727,981 Lomasney May 12, 1903 766,978 Symington Aug. 9, 1904 838,250Hudlow Dec. 11, 1906 1,281,512 Carothers Oct. 15, 1918 1,596,727Goldberg Aug. 17, 1926 1,836,482 Lyon et a1 Dec. 15, 1931 2,224,959Galloway Dec. 17, 1940 2,396,281 Noble et al Mar. 12, 1946 2,436,873Sneva Mar. 2, 1948 2,552,164 Foss May 8, 1951

